US6296643B1 - Device for the correction of spinal deformities through vertebral body tethering without fusion - Google Patents

Abstract

A fusionless method of treating spinal deformities in the spine of a child or young adult involves attaching a tether to vertebral bodies on the convex side of the spine. Deformities are treated by using the tether to selectively constrain growth in a portion of the convex side of the spine. One device for tethering the spine is a combination of a strand threaded through channels defined in a set of blocks attached to the vertebral bodies on the convex side of the spine.

Description

This application claims the benefit of U.S. Provisional Application No. 60/130,909, filed Apr. 23, 1999.

BACKGROUND OF THE INVENTION

Current operative methods for treating spinal deformities, particularly scoliosis, include correction of the curve by some internal fixation device, and fusion of the spine in the corrected state usually accomplished by the placement of bone graft between vertebrae. This is usually accomplished with posterior surgery, although anterior procedures are becoming more popular, as well as combinations of anterior and posterior procedures. Several instrumentation systems are available from various manufacturers to correct and stabilize the spine while fusion occurs. Among them are TSRH®, CD™, CD Hopf™, CD Horizon™, ISOLA™, Moss Miami and Synthes Universal Spine Systems. Nonoperative methods do exist and are used when applicable. These nonoperative methods include bracing and observation.

Juvenile idiopathic scoliosis occurs between the ages of 4 and 10 years. It can resolve spontaneously, respond to nonoperative therapy, or progress until fusion is required. Stapling across long bone physes has long been recognized as a predictable method of treating limb malalignment. Vertebral interbody stapling across the cartilaginous endplates and discs was attempted by Nachlas and Borden in a canine scoliosis model. Early human results in the 1950s were disappointing. Roaf reported limited successful correction of scoliosis by uninstrumented convex hemiepiphysiodesis. His study did not have a uniform patient population by skeletal maturity or scoliosis etiology.

Further shortcomings of current operative methods and devices are numerous. Patients with juvenile scoliosis who undergo curve stabilization with subcutaneous rods would be subject to multiple surgical procedures for lengthening as they grow. Anterior and/or posterior spinal fusion in the skeletally immature patient often results in loss of vertebral body height and girth. Additionally, poor self-image may occur in adolescent patients who are braced for scoliosis. Moreover, curve stabilization with bracing is only successful in approximately 75% of patients. Another problem is that some children, while not currently candidates for a definitive fusion procedure, are likely to need such a procedure in the future. These would include children less than ten years of age, small in stature, premenstrual or riser two or lower, and those not physically able to tolerate the surgery required for a definitive fusion procedure. It would be preferable to eliminate the need for that procedure altogether.

SUMMARY OF THE INVENTION

One embodiment of the invention is a device for restraining growth in a spine having a convex side and a concave side. The device comprises a strand, at least two blocks and a plurality of fasteners. Each block has a top surface, bottom surface and a first and second set of opposing side surfaces. The block is oriented on the spine so that the first set of side surfaces are located on an anterior part and a posterior part respectively of the spine. The block has a generally curved shape in a transverse direction from the anterior part to the posterior part corresponding to the antero-lateral anatomy of vertebral bodies. The bottom surface of the block is configured to contact a vertebral body. At least one fastener connects each block to at least one vertebra on the convex side of the spine. Each block has at least one channel for receiving the strand. Each block also has at least one bore extending between the top and bottom surfaces of the block. The bore receives one of the fasteners which connect the block to a vertebral body.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of an embodiment of a tether of the present invention including a set of blocks and fasteners with a strand threaded through channels in the blocks.

FIG. 2 is a side view of the embodiment of FIG. 1

FIG. 3 is a top view of an alternative to the embodiment of FIG. 1 where the strand is an adjustable spinal tether in a figure eight configuration.

FIG. 4 is a top view of an alternative to the embodiment of FIG. 3 with the tether in a straight loop configuration.

FIG. 5 is a perspective view of another embodiment in which the channels open through the top surface of the blocks.

FIG. 6A is a schematic illustration of the embodiment of FIG. 1 attached to vertebral bodies on the convex side of a child's scoliotic spine.

FIG. 6B is a schematic illustration of an alternative embodiment of FIG. 6A where the strand is knotted in between the blocks.

FIG. 7A is a schematic illustration of the embodiment of FIG. 3 attached to vertebral bodies on the convex side of a spine.

FIG. 7B is a schematic illustration of an alternative embodiment of FIG. 7A where the adjustable strand is crimped in between the blocks.

FIG. 8A is a cross-sectional view of one embodiment of the interconnection between the fasteners and the blocks.

FIG. 8B is a cross-sectional view of another embodiment of the interconnection between the fasteners and the blocks having a screw back-out mechanism.

FIG. 9 is a cross-sectional view of another embodiment of the interconnection between the fasteners and the blocks.

FIG. 10A is a side view of another embodiment of a block.

FIG. 10B is a top view of the embodiment of the block of FIG.10A.

FIG. 10C is another side view of the embodiment of the block in FIG.10A.

FIG. 10D is a perspective view of the embodiment of the block of FIG.10A.

FIG. 10E is another top view of FIG. 10A illustrating further detail of the embodiment of the block.

FIG. 10F is a cross-sectional view along the line10F in FIG.10E.

FIG. 10G is another cross-sectional view of FIG. 10E along the line10G.

FIG. 10H is another side view of the embodiment of FIG. 10A illustrating further detail.

FIG. 10I is a cross-sectional view of FIG.1OH along the lines10I.

DESCRIPTION OF THE PREFERRED EMBODIMENT

For the purposes of promoting an understanding of the principles of the invention, reference will now be made to the embodiment illustrated in the drawings and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the invention is thereby intended, such alterations and further modifications in the illustrated device, and such further applications of the principles of the invention as illustrated therein being contemplated as would normally occur to one skilled in the art to which the invention relates.

Various devices and surgical approaches are possible to implement the underlying idea of this invention. That idea is the correction of spinal deformities, particularly scoliosis, through fusionless tethering. The correction of the deformity is achieved by attaching a tether to the vertebral bodies on the convex side of the spine. This tether will minimize or arrest growth on the convex or “long” side of the spine and allow the concave or “short” side of the spine to grow and catch up with the long side. Alternatively, fusionless tethering may treat abnormal spinal alignment by simply preventing further misalignment such as curve progression.

A wide variety of surgical approaches may be used in implementing tethering of the convex side. One approach is an open thoracotomy (standard). Another surgical approach contemplated is a minimally invasive thoracoscopic approach (endoscopic). The surgical approach may also be a combined anterior/posterior approach (standard or endoscopic). It should be understood that the invention can be practiced using other surgical approaches known to persons of ordinary skill in the art.

In any surgical approach used in practicing the invention, the tether used to selectively constrain growth will include at least one longitudinal element and one anchor with an interconnection between the longitudinal element and the anchor. In some cases the longitudinal element and the anchor may be one and the same. The following discusses generally some of the types of apparatus that may be used. Additionally, it should be understood that most, if not all, of the longitudinal elements or anchors may be manufactured from, but are not limited to, conventional implant metals, such as stainless steel or titanium. It should be further understood, and will be discussed in some detail for particular embodiments, that the longitudinal elements and anchors may take advantage of the shape memory and superelastic characteristics of shape memory materials including, for example, a shape memory alloy (“SMA”) such as nickel titanium.

Several devices are contemplated for spanning the longitudinal aspect of the spine during the fusionless tethering procedure. A list of potential longitudinal elements includes, but is not limited to, staples, cables, artificial strands, rods, plates, springs, and combinations of devices from the foregoing list. Details of each individual element will be discussed briefly.

The longitudinal element may be a spinal staple formed in a variety of shapes and sizes depending on its application. Staples may act as either the longitudinal element, the anchor, or both. These staples may be manufactured from conventional implant metal, such as stainless steel or titanium. In one preferred embodiment, however, the staples are manufactured out of shape memory materials or alloys such as nickel titanium to enhance fixation. One example of such an alloy is Nitinol sold by Memry Corporation of Menlo Park, Calif. Further details of preferred use, size, and material selection for the spinal staple may be found in copending patent application U.S. Ser. No. 09/421,903 entitled “Shape Memory Alloy Staple” filed on the same day as the present application and commonly assigned to the assignee of the present application, the disclosure of which is incorporated herein by reference.

Another possible selection for the longitudinal element is cabling. Historical spinal instrumentation involved the use of cables (Dwyer) as a fixation method for spinal fusion. However, this use of cable never contemplated that a flexible cable could represent the longitudinal element in a fusionless tethering procedure.

The use of artificial or synthetic strands, much in the same way cable could be used, may potentially add additional flexibility and motion to this fusionless tethering procedure. In one preferred embodiment the artificial strand may be manufactured from a braided polymer rope. In another preferred embodiment the artificial strand will be an adjustable spinal tether. Details of various embodiments of the adjustable spinal tether may be found in provisional patent application Ser. No. 60/130,910, entitled “Adjustable Spinal Tether” filed on Apr. 23, 1999 and commonly assigned to the assignee of the present application, the disclosure of which is incorporated herein by reference. Such an artificial strand is preferably (but not necessarily) used in conjunction with a block similar or identical to various embodiments of the “Hopf blocks” disclosed in U.S. Pat. No. 5,702,395 to Hopf entitled “Spine Osteosynthesis Instrumentation for an Anterior Approach” the disclosure of which is incorporated herein by reference. It is contemplated as within the scope of the invention, however, that the artificial strand may be utilized for fusionless tethering in a variety of manners. These include, but are not limited to, being attached to or around anchors such as screws and staples. It is further contemplated as within the scope of the invention that the artificial strand may also act as both the longitudinal element and the anchor by being secured directly around the vertebrae to be tethered.

Another possible selection for the longitudinal element is a flexible rod. These could be manufactured of small diameter and/or flexible material such as a super elastic SMA. In a similar manner plates may be used as a longitudinal element. The plates can be used with or without slots allowing implants to slide. Another possible choice is a spring. Springs have been used historically in spinal instrumentation and could form the longitudinal element. Again, to reiterate, it should be understood that combinations of any or all of the above may be used as a longitudinal element when deemed appropriate.

Most of the longitudinal elements discussed above, the staples and artificial strands being possible exceptions, will need to be anchored to the vertebral bodies in order to effectively tether them. Several different anchors are contemplated.

As previously mentioned, staples can be both anchors as well as longitudinal elements since they possess the characteristics of both. These staples can be either conventional or a SMA as stated above. Also available for use in this capacity are scaled up suture anchor type products. Novel approaches using such products known in the art are available to fix to soft cancellous bone such as that found in a vertebral body. Additionally, screw down fixation plates, posts, etc. as are known to those of ordinary skill in the art, may be used as anchors.

Another potential anchor is an expandable screw. Examples include Mollie bolt type implants that are initially screwed into the vertebral body and expand through some mechanism. It is again possible to take advantage of the properties of shape memory materials to accomplish the expansion mechanism. Conventional screws and bone screws may also serve as anchors. These screws may be coated with any number of osteoinductive or osteoconductive materials to enhance fixation as desired.

The selection of the longitudinal elements and anchors from those previously discussed and others known in the art also leaves possible the selection of a wide variety of interconnections between the two. Once the anchors are in place, their connection to the longitudinal elements can be governed by a number of different parameters. They could be constrained or unconstrained connections; the anchor could be allowed to slide along the longitudinal element or articulate with it, as in the case of a ball joint, or even float within some neutral zone. Several scenarios are envisioned.

The first is constrained. This would involve constrained interconnection scenarios between all anchors and longitudinal elements. The second is unconstrained. This would involve simple connections in which no significant restrictions exist between the longitudinal element and the anchor. An example is an artificial strand band around a post, or a screw through an artificial strand ribbon.

The third scenario is ends constrained with middle elements unconstrained. In this case the construct would possess constrained interconnections between the end anchors and the longitudinal elements with unconstrained interconnections in between. These unconstrained interconnections could be either sliding situations or ball joint situations. The fourth scenario is ball joint interconnections. Ball joints represent a semiconstrained situation in which the anchor cannot slide up or down the longitudinal element, but can articulate within some spherical range of motion. It should be understood that combinations of any or all of the above may be used as appropriate in practicing the present invention.

The above disclosure deals specifically with the broad range of device concepts envisioned for fusionless tethering of deformities in order to achieve permanent correction. The specifics with regard to the method are similarly broad. A wide range of spinal deformities could be managed. The primary indications will be progressive idiopathic scoliosis with or without sagittal deformity in either infantile or juvenile patients. The preferred patient population upon which to practice the present invention is prepubescent children (before growth spurt) less than ten years old. Other patient groups upon which the present invention may be practiced include adolescents from 10-12 years old with continued growth potential. It should be understood that fusionless tethering may be used on older children whose growth spurt is late or who otherwise retain growth potential. It should be further understood that fusionless tethering may also find use in preventing or minimizing curve progression in individuals of various ages.

Generally, in the case of scoliosis, tethering will take place on the convex side of the curve. An anterior, minimally invasive (thoracoscopic) procedure can be carried out on the convex side of the spinal curve in order to prevent continued growth on that side of the curve. As the pre-growth spurt child approaches puberty, the untethered side of the spine will grow unconstrained, ultimately eliminating the curvature of the spine in the frontal plane. It is preferable to deliver this method of treatment in a minimally invasive approach using thoracoscopic instrumentation. It is contemplated as within the scope of the invention, however, that open use of these systems may be appropriate in some cases. It is further contemplated as within the scope of the invention that the procedure may be posterior as well as anterior, or some combination of both. Finally, it should be understood that if the procedure fails to correct the curve but does, in fact, prevent further progression (which includes increase in the magnitude of the curve) it can and should be considered successful.

In one embodiment of the invention, fusionless correction of scoliosis is achieved by thoracoscopically placing shape memory alloy staples into the vertebral bodies on the convex side of the spine. The staples will span the intervertebral space and act as a tether on the spine. This tether will arrest growth on the convex (“long”) side of the spine and allow the concave (“short”) side of the spine to grow and catch up with the long side. Once correction is achieved, the staple may then be removed thoracoscopically if desired. The removal of the staples permits further growth of the vertebral bodies. It should be understood that the method described is equally applicable in non-endoscopic procedures. It should be further understood that the staples used may be made of a conventional implant metal such as titanium or stainless steel instead of a SMA.

Further details regarding the method of using spinal staples for the fusionless correction of scoliosis as well as details regarding the staples themselves may be found in U.S. provisional application entitled “Device and Method for the Correction of Spinal Deformities Through Vertebral Body Tethering Without Fusion” U.S. Ser. No. 60/130,909 filed Apr. 23, 1999 and U.S. application entitled “Shape Memory Alloy Staple” U.S. Ser. N0.09/421,903 filed the same day as the present application. Animal studies are currently ongoing comparing the utility of spinal staples versus a device using the blocks and strands discussed in more detail below.

Another device useful for correction of spinal deformities through fusionless tethering involves the use of blocks similar or identical to those disclosed in the above mentioned U.S. Pat. No. 5,702,395 to Hopf titled “Spine Osteosynthesis Instrumentation for an Anterior Approach” along with cabling or artificial strands. Several preferred embodiments for use as an artificial strand are disclosed in the above mentioned provisional patent application Ser. No. 60/130,910 entitled “Adjustable Spinal Tether.”

With reference to FIGS. 1 and 2, one embodiment includes a set of three blocks with corresponding fasteners and a synthetic strand or cable threaded through channels in the blocks is shown. It should be understood that anywhere from two to greater than five blocks may be used. In one preferred embodiment the number of blocks is three. Eachblock10 has atop surface11 and abottom surface12 along with first and second sets of opposing side surfaces. Theblock10 is oriented so that in the first set, side surfaces13,14 are located on an anterior and a posterior part respectively of the spine (see also FIGS.6 and7). Theblock10 has a generally curved shape in a transverse direction from theanterior surface13 to theposterior surface14 corresponding to the antero-lateral anatomy of vertebral bodies. Thebottom surface12 is configured to contact a vertebral body.

Eachblock10 has a second set of side surfaces15,16 which are oriented substantially upward and downward along the longitudinal axis S_kof the spine (see FIGS.6 and7). Theupper surface15 andlower surface16 of eachblock10 define at least one opening or channel for receivingsynthetic strand38. In an embodiment with only one channel, the channel must either have a post or divider somewhere along its length around which thestrand38 is wrapped or else thestrand38 may be threaded through the channel and around either thetop surface11 orbottom surface12 of eachblock10. In one preferred embodiment (see FIG.1), eachblock10 has two substantially parallel channels, ananterior channel20 and aposterior channel21.Anterior channel20 andposterior channel21 extend in a direction along a line connectingupper surface15 andlower surface16. It is contemplated as within the scope of the invention thatanterior channel20 andposterior channel21 may extend in different directions and/or be curved in betweenupper surface15 andlower surface16. It is further contemplated as within the scope of the invention thatanterior channel20 andposterior channel21 may be at an angle with respect to either or both ofupper surface15 andlower surface16. Moreover,channels20 and21 may both be closer toanterior surface13 thanposterior surface14 or vice versa. Selection of various channel orientations permits configurations for the synthetic strand other than the figure eight or straight loop configuration discussed below. Also, it should be understood that the channels such as20 and21 may instead connect the first set of opposing side surfaces13 and14 or may connect some combination of the first and second sets of opposing side surfaces.

Additionally, eachblock10 further defines at least one bore extending betweentop surface11 andbottom surface12. Eachblock10 may have one or more bores for receiving a fastener to connect each block to a vertebral body. In onepreferred embodiment block10 has two bores, ananterior bore22 and aposterior bore23. It should be understood that eachblock10 may have only one bore or more than two depending on the number of fasteners a surgeon wishes to use to attach each block to a vertebral body. Each bore22,23 extends between thetop surface11 andbottom surface12 ofblock10.Bores22,23 are defined inblock10 with dimensions such that each bore may receive one of the fasteners used to attach theblock10 to the vertebral body.

The bottom portion ofbores22,23 nearbottom surface12 are preferably sized to snugly receive theheads32,33 offasteners30,31. With reference to FIG. 8A in which like elements are labeled as previously, it is seen that bore22 has atop portion22aandbottom portion22b. Similarly bore23 has atop portion23aand abottom portion23b.Top portions22aand23aare preferably (but not necessarily) tapered for facilitating insertion offasteners30,31 throughbores22,23 respectively. Thehead32 offastener30 has atop portion32awith a notch therein for receiving a driving mechanism and abottom portion32bconfigured to engage thebottom portion22bofbore22. Similarly, thehead33 offastener31 has atop portion33awith a notch therein for receiving a driving mechanism and abottom portion33bconfigured to engage thebottom portion23bofbore23.

With reference to FIG. 8B, an alternative embodiment is shown with a mechanism to aid in the prevention of screw back out. With reference to FIG. 8B, in which like elements are labeled as previously, it is seen that bore122 has atop portion122aandbottom portion122b. Similarly, bore123 has atop portion123aand abottom portion123b.Top portions122aand123aare preferably (but not necessarily) tapered for facilitating insertion offasteners130,131 throughbores122,123 respectively. Thehead132 offastener130 has atop portion132awith a notch therein for receiving a driving mechanism and abottom portion132bconfigured to engage thebottom portion122bofbore122. Similarly, thehead133 offastener131 has atop portion133awith a notch therein for receiving a driving mechanism and abottom portion133bconfigured to engage thebottom portion123bofbore123. Thehead132 offastener130 hasexternal threading132cdefined thereon which engages threading122cdefined inbore122 and aids in the prevention of screw back out. Similarly, thehead133 offastener131 has threading133cdefined on thehead133 which engages threading123cdefined inbore123.

It should be understood that bores22,23 may also be sized to loosely receiveheads32 and33. The bottom portion ofbores22,23 and heads32,33 may both be shaped for ball and socket interconnection allowing the pivoting or swiveling of the connecting portion offasteners30,31 relative to eachblock10. With reference to FIG. 9 in which like elements are labeled as previously, thebottom portions32b′,33b′ ofheads32,33 are hemispherical as are thebottom portions22b′,23b′. Again thetop portions22a,23aare preferably tapered to facilitate insertion of the fasteners through the bores. Alternatively, in another embodiment thebores22,23 and heads32,33 may be shaped for engagement such that the angle of thefasteners30,31 with respect to each other and theblock10 is substantially fixed. It should be understood that in either case, it may be desirable in some situations to use a screw back out system as described with reference to FIG. 8B or others known in the art.

In one embodiment, bore22 intersects withchannel20 and bore23 intersectschannel21. It should be understood, however, that thebores22,23 need not intersectchannels20,21. In the embodiment where thebores22,23 intersect thechannels20,21, each bore is preferably defined in such a manner that the top ofheads32,33 offasteners30,31 are not withinchannels20,21 whenfasteners30,31 are in the bottom portion ofbores22,23 (see FIGS. 3,6, and7). As a result, strand orcable38 is unobstructed when threaded throughchannels20,21.

With reference to FIG. 1, theartificial strand38 may be a strand with two ends tied or spliced together (see FIGS.6A and6B). Theartificial strand38 may be made of any suitable biocompatible material such as stainless steel or titanium or a polymer such as polyester or polyethylene. With reference to FIG. 3, another embodiment has adjustablespinal tether40 threaded through thechannels20,21 ofblocks10. Adjustablespinal tether40 has a strand orcable portion39 having afirst end41 and asecond end42. First end41 ends in aleader43 for ease of threading adjustablespinal tether40 through thechannels20,21 inblocks10. Theleader43 may be an extrusion offirst end41 or may be otherwise affixed ontofirst end41 by press fitting, adhesive, or other means known in the art. Details of various embodiments of the adjustable spinal tether construction may be found in the above mentioned patent application titled “Adjustable Spinal Tether.”

Second end42 may be wrapped around or otherwise attached to agrommet44. In an alternative embodiment the adjustable spinal tether may havesecond end42 looped around on itself to form an eyelet (not shown) without the need for a grommet. Theleader43 andfirst end41 are threaded throughgrommet44 and crimp45 attached to thegrommet44.Crimp45 has external threading47 matching internal threading (not shown) onlock nut46.Lock nut46 is tightened down oncrimp45 to securecrimp45 on strand orcable39 when the appropriate length is threaded through thechannels20,21 ofblocks10 and drawn taut. The excess length ofstrand39 may then be trimmed off abovecrimp45. With reference to FIGS. 1,3 it is seen that thestrand38,39 may be threaded throughblocks10 in a figure eight configuration. With reference to FIG. 4, in an alternative embodiment it is seen that thestrand38 may also be threaded throughblocks10 in a straight loop configuration. It should be understood that for all embodiments thestrand38 or adjustablespinal tether40 may be threaded through the channels in theblocks10 in either a figure eight or loop configuration or any combination of both as desired.

With reference to FIG. 5, in yet another embodiment blocks10′ are shown with like elements labeled as previously.Blocks10′ haveanterior channel20′ andposterior channel21′. In this embodimentanterior channel20′ andposterior channel21′ extend betweenupper surface15′ andlower surface16′ as well as up throughtop surface11′. Additionally,anterior channel20′ andposterior channel21′ are defined such that the portion nearer tobottom surface12 is slightly offset from that defined intop surface11′. Thechannels20′,21′ inblocks10′ permit thesynthetic strand38 to be inserted intoblocks10′ throughtop surface11′. Sincechannels20′,21′ have a slightly offset region nearer to thebottom surface12, whensynthetic strand38 is drawn taut it is secured within the channels and will not slip out throughtop surface11′.

With reference to FIG. 6A, blocks10 are shown attached tovertebral bodies60 withartificial strand38 spanningintervertebral discs61. The ends ofstrand38 are shown tied together in a knot65. It should be understood that a variety of knots may be used in place of knot65. For example, with reference to FIG. 6B, in which like elements are labeled as previously, the knot65amay be tied in an intermediate location between two of the vertebral blocks11 as opposed to knot65 as seen in FIG.6A.

With reference to FIG. 7A, blocks10 are again shown attached tovertebral bodies60. In this embodiment theintervertebral discs61 are spanned by anartificial strand39 which is part of adjustablespinal tether40. With reference to FIG. 7B, as in the embodiment disclosed in FIG. 6, thecrimp45 may be at an intermediate location between blocks. With reference to FIGS. 6A,6B,7A, and7B, it should be noted that the arrow S_kparallels the longitudinal axis of the spinal column made up of vertebral bodies and intervertebral discs.

With reference to FIGS. 10A-I, another embodiment of an anterior block for spine tethering is shown. Eachblock510 has atop surface511, abottom surface512,intermediate surfaces551,552, and first and second sets of opposing side surfaces. Theblock510 is oriented so that the first set of side surfaces513a,513b, and514a,514bare located on an anterior and a posterior part respectively of the spine (similar to side surfaces13 and14 in FIGS.6 and7). The first set of side surfaces includes an upperanterior side surface513aand a loweranterior side surface513band an upperposterior side surface514aand lowerposterior side surface514b. Theblock510 has a generally curved shape in a transverse direction from the loweranterior surface513bto thelower posterior surface514bcorresponding to the antero-lateral anatomy of vertebral bodies. Thebottom surface512 is preferably (but not necessarily) configured to contact the vertebral body.

Eachblock510 has a second set of side surfaces515,516 which are oriented to face substantially upward and downward along the longitudinal axis of the spine, similar to side surfaces15,16 in FIGS. 6 and 7. Theupper surface515 andlower surface516 of eachblock510 define at least one opening or channel for receiving a synthetic strand or adjustable spinal tether. In an embodiment with only one channel, the channel must either have a post or divider somewhere along its length around which the strand or adjustable spinal tether is wrapped or, alternatively, the strand or adjustable spinal tether may be threaded through the channel and around either thetop surface511 orbottom surface512 of eachblock510. In one preferred embodiment (see FIGS.10A-I), eachblock510 has two substantially parallel channels, ananterior channel520 and aposterior channel521.Anterior channel520 andposterior channel521 extend in a direction along a line connectingupper surface515 andlower surface516. It is contemplated as within the scope of the invention thatanterior channel520 andposterior channel521 may extend in different directions and/or be curved in betweenupper surface515 andlower surface516. It is further contemplated as within the scope of the invention thatanterior channel520 andposterior channel521 may be at an angle with respect to either or both ofupper surface515 andlower surface516. Moreover,channels520 and521 may both be closer to anterior surface513 thanposterior surface514 or vice versa. Selection of various channel orientations permits configurations for the synthetic strand or adjustable spinal tether or than the figure eight or straight loop configuration shown in FIGS. 3 and 4 with reference to a previously described embodiment of the block. Also, it should be understood that the channels such as520 and521 may instead connect the first set of opposing upper side surfaces513aand514aor may connect some combination of the first and second sets of opposing side surfaces.

Additionally, eachblock510 further defines at least one bore extending betweentop surface511 andbottom surface512. Eachblock510 may have one or more bores for receiving a fastener or connect each block to a vertebral body. In one preferred embodiment, block510 has two bores, ananterior bore522 and aposterior bore523. It should be understood that eachblock510 may have only one bore or more than two depending on the number of fasteners a surgeon wishes to use to attach each block to a vertebral body. Eachbore522,523 extends between thetop surface511 andbottom surface512 ofblock510.Bores522,523 are defined inblock510 with dimensions such that each bore may receive one of the fasteners used to attach theblock510 to the vertebral body.

It should be understood that the bores of this embodiment of the anterior block may include features similar to those described in the previous embodiment and shown in FIGS. 8 and 9. In other words, the bores may have tapered surfaces for facilitating insertion of fasteners, may be shaped for a ball and socket interconnection, may have matching threading on the head of a fastener to prevent screw back out and the bores may be arranged in a variety of angles with respect to each other. These and other features were previously described with reference to the embodiment shown in FIGS. 8 and 9.

To better illustrate the construction of theblock510, the dimensions of one manufactured embodiment are hereafter listed. It should be understood, however, that these dimensions are exemplary and not intended to limit the scope of protection sought. The use of dimensions and tolerances other than those listed are contemplated as within the scope of the invention. With reference to FIG. 10A,length530 is 6 mm,length531 is 6.7 mm,length532 is 2.33 mm,angle533 is 30 degrees, andangle534 is 20 degrees. With reference to FIG. 10B,length535 is 17.82 mm,length536 is 19.16 mm,length537 is 26.39 mm, and angles538aand538bare both preferably 20 degrees. With reference to FIG. 10C,length539 is 15 mm,length540 is 7.5 mm, andlength541 is 15 mm. With reference to FIG. 10E,length542 is 10.5 mm,543 is 4.5 mm. With reference to FIG. 10F,length544 is 10.6 mm,length545, which defines the diameter ofbore523 at one point is 6.4 mm,length546 is 20,length547, which defines the diameter of the bore at one point, is 6 mm,length548, which defines the minimum diameter of the bore is 5.05 mm, andangle549 is five degrees. With reference to FIG. 10G,length560 is 8.4 mm, andlength563 is 7 mm,angle564 is 15 degrees andangle565 is 10 degrees. With reference to FIG. 10H,length570 is 3.1 mm,length571 is 7 mm,length572 is 12 mm, andangle573 is 10 degrees. With reference to FIG. 10I,length574 is 4.53 mm,length575 is 1 mm,length576 is 16.85 mm,length577 is 11.35 mm,length578 is 7.5 mm,length579 is 3.53 mm,length580 is 2 mm,length581 is 11.85 mm,length582 is 17.35 mm, and angles583 and584 are both 20 degrees. As previously mentioned, variations in these design parameters that would occur to a person of ordinary skill in the art are contemplated as within the scope of the invention.

It should be understood that the just described embodiment of a block may be used in various manners similar or identical to those shown in FIGS. 1-7 with an artificial strand or adjustable tether. The advantages of this embodiment include the reduction in the amount of volume and the amount of metal. By essentially removing portions of what was a previously rectangular cross section, this embodiment of the block has a lower profile and is less bulky.

While the invention has been illustrated and described in detail in the drawings and foregoing description, the same is to be considered illustrative and not restrictive in character, it being understood that only the preferred embodiments have been shown and described and that all changes and modifications that come within the spirit of the invention are desired to be protected.

Claims (39)

What is claimed is:

1. A device for treating a spinal curvature without fusion, comprising:

a plurality of bone anchors, at least one of said bone anchors adapted to engage a respective one of at least two vertebra on a convex side of the spinal curvature;

a plurality of connectors, one of said connectors being coupled to said at least one of said bone anchors; and

a strand extending between and interconnecting said connectors to restrain progression of the spinal curvature.

2. The device of claim1 wherein said strand restrains growth of the spine on the convex side of the spinal curvature.

3. The device of claim1 wherein each of said connectors defines at least one opening, said strand being disposed within each said at least one opening and made taut to interconnect said connectors.

4. The device of claim3 wherein said at least one opening opens onto an outer surface of each of said connectors to allow said strand to be inserted transversely into said at least one opening.

5. The device of claim3 wherein said at least one opening is a channel extending through each of said connectors; and

wherein said strand has a first end portion and a second end portion, said strand being received within each of said channels with said first and second end portions being coupled together to form a continuous strand.

6. The device of claim5 wherein each of said connectors defines a pair of said channels, said strand being threaded through said pair of channels in each of said connectors in a loop configuration.

7. The device of claim5 wherein each of said connectors defines a pair of said channels, said strand being threaded through said pair of channels in each of said connectors in a figure eight configuration.

8. The device of claim1 wherein said bone anchors are bone screws, each of said connectors defining at least one bore extending therethrough and adapted to receive a respective one of said bone screws therein to engage said connectors to said at least two vertebra.

9. The device of claim1 wherein said strand is formed of a synthetic material.

10. The device of claim1 wherein said strand is formed of a polymer.

11. The device of claim10 wherein said polymer is polyethylene.

12. The device of claim1 wherein said strand is formed of a metal.

13. The device of claim1 wherein said strand comprises a braided rope.

14. The device of claim1 wherein said strand comprises an adjustable spinal tether.

15. A device for treating a spinal curvature without fusion, comprising:

a plurality of bone anchors, at least one of said bone anchors adapted to engage a respective one of at least two vertebra on a convex side of the spinal curvature;

a plurality of blocks, one of said blocks being coupled to said at least one of said bone anchors, each of said blocks defining a bottom surface and a pair of opposite side surfaces extending from said bottom surface, one of said side surfaces being disposed adjacent an anterior portion of the spine and another of said side surfaces being disposed adjacent a posterior portion of the spine, said bottom surface defining a curved portion extending transversely between said pair of opposite side surfaces, said curved portion engaging a correspondingly shaped portion of said respective one of said at least two vertebra; and

a strand extending between and interconnecting said connectors to restrain progression of the spinal curvature.

16. The device of claim15 wherein said strand restrains growth of the spine on the convex side of the spinal curvature.

17. The device of claim15 wherein said correspondingly shaped portion is the antero-lateral anatomy of said respective one of said at least two vertebra.

18. The device of claim15 wherein each of said blocks is a single piece structure defining at least one opening, said strand being threaded through said at least one opening in each of said blocks and made taut to interconnect said connectors.

19. The device of claim18 wherein said at least one opening and each of said opposite side surfaces are oriented in a substantially parallel relationship.

20. The device of claim15 wherein each of said blocks defines a top surface, said at least one opening being a channel extending through each of said blocks and opening onto said top surface to allow said strand to be inserted transversely into said channel.

21. The device of claim15 wherein said bone anchors are bone screws, each of said blocks defining a top surface and including at least one bore extending between said top and bottom surfaces, said bore being adapted to receive a respective one of said bone screws therein to engage said blocks to said at least two vertebra.

22. A device for treating a spinal curvature without fusion, comprising:

a plurality of bone anchors, at least one of said bone anchors adapted to engage a respective one of at least two vertebra on a convex side of the spinal curvature;

a plurality of connectors, one of said connectors being coupled to said at least one of said bone anchors, each of said connectors defining at least one opening extending therethrough; and

a strand having a first end portion and a second end portion, said strand being threaded through said at least one opening in each of said connectors with said first end portion being coupled to said second end portion to form a continuous strand.

23. The device of claim22 wherein said strand restrains progression of the spinal curvature.

24. The device of claim22 wherein said strand constrains growth of the spine on the convex side of the spinal curvature.

25. The device of claim22 wherein said strand is an adjustable spinal tether.

26. The device of claim22 wherein said second end portion defines a passage, said strand being made taut by pulling said first end portion through said passage.

27. The device of claim26 further comprising a leader affixed to said first end portion, said second end portion including a loop defining said passage, said strand being made taut by inserting said leader through said loop and pulling said first end portion through said loop.

28. The device of claim26 wherein said first and second end portions are knotted together to form said continuous strand.

29. The device of claim22 wherein said first and second end portions are knotted together to form said continuous strand.

30. The device of claim22 wherein each of said connectors defines a pair of said openings extending therethrough, said strand being threaded through said pair of said openings in each of said connectors in a loop configuration.

31. The device of claim22 wherein each of said connectors defines a pair of said openings extending therethrough, said strand being threaded through said pair of said openings in each of said connectors in a figure eight configuration.

32. The device of claim22 wherein said bone anchors are bone screws, each of said connectors defining at least one bore extending therethrough and adapted to receive a respective one of said bone screws therein to engage said connectors to said at least two vertebra, said at least one bore intersecting said at least one opening.

33. A device for restraining growth and/or curve progression in a spine without fusion, the spine having a convex side and a concave side, comprising:

at least two blocks, each of said blocks adapted to be coupled to a respective vertebrae on the convex side of the spine by at least one fastener, each of said blocks comprising a single piece structure and including at least one channel extending therethrough; and

a strand threaded through said at least one channel in each of said blocks to interconnect said blocks.

34. The device of claim33 wherein each of said blocks includes a pair of opposite side surfaces, said block being oriented so that one of said side surfaces is positioned adjacent an anterior part of the spine and another of said side surfaces is positioned adjacent a posterior part of the spine.

35. The device of claim34 wherein each of said blocks includes a bottom surface extending transversely between said pair of opposite side surfaces, said bottom surface defining, a curved portion extending in a transverse direction and configured to engage a correspondingly shaped portion of said respective vertebrae.

36. The device of claim35 wherein said correspondingly shaped portion is the antero-lateral anatomy of said respective vertebrae.

37. The device of claim33 wherein each of said blocks has a generally curved shape and defines a surface configured to bear against said respective vertebrae, said surface corresponding to the antero-lateral anatomy of said respective vertebrae.

38. The device of claim33 wherein said strand has a first end portion and a second end portion, said first and second end portions being coupled together to form a continuous strand.

39. The device of claim38 wherein said second end portion defines a passage, said strand being made taut by pulling said first end portion through said passage, said first and second end portions being knotted together to form said continuous strand.

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